两个人如何在句号分隔的句子中以任何顺序找到两个单词

Question

我正在尝试提取任何包含两个单词column 和Barr 的句子（定义为在两个句点之间）。这很棘手，因为目前我创建了一个正则表达式，它只能在句点之前以任何顺序查找两个单词，但如果这两个单词出现在两个句子中，则选择两个句子之间的所有文本。如何使正则表达式语句具体化？

输入

try<-c("I am a sentence.I am a sentence and I contain Barr. I contain other things. I contain column as well.","Here we go. I am a sentence and I contain column but also Barr. I only contain Barr. I am too.")

期望的输出

[1] NA
[2] "I am a sentence and I contain column but also Barr.

尝试

str_extract_all(try,"\..*column.Barr.?\.|.*Barr.column.?\.")

电流输出

[[1]]
[1] "I am a sentence.I am a sentence and I contain Barr. I contain other things. I contain column as well."

[[2]]
[1] ". I am a sentence and I contain column but also Barr. I only contain Barr."

Answer 1

为了找到以任意顺序出现的两个单词，您可以使用两个正向前瞻： 例如grepl((?=.*Barr)(?=.*column),x,perl=T) 将在每次出现两个单词时返回TRUE，无论它们的顺序如何，否则返回FALSE，但这没有考虑句子结构。 由于您要提取文本，并且要查找点之间的两个单词，我们可以将其更改为：

library(stringr)
## Example data
x <- c("I am a sentence.I am a sentence and I contain Barr. I contain other things. I contain column as well.","Here we go. I am a sentence and I contain column but also Barr. I only contain Barr. I am too.","Barr and column and also column. But just Barr. And just column. Now again column and Barr")
> x
[1] "I am a sentence.I am a sentence and I contain Barr. I contain other things. I contain column as well."
[2] "Here we go. I am a sentence and I contain column but also Barr. I only contain Barr. I am too."       
[3] "Barr and column and also column. But just Barr. And just column. Now again column and Barr"           

str_extract_all(x,"(\\.|^)(?=[^\\.]*Barr)(?=[^\\.]*column)[^\\.]*(\\.|$)")

这将查找句首或句点(\\.|^)，后跟不是句点且包含Barr 和列(?=[^\\.]*Barr)(?=[^\\.]*column)[^\\.]* 的字符，后跟句号或句尾(\\.|$)。 这会返回一个列表：

[[1]]
character(0)

[[2]]
[1] ". I am a sentence and I contain column but also Barr."

[[3]]
[1] "Barr and column and also column." ". Now again column and Barr"

Answer 2

这个正则表达式似乎可以满足您的需要：

(\\.[^.]*column[^.]*Barr[^.]*)|(\\.[^.]*Barr[^.]*column[^.]*)

它将从一个点 (.) 开始，并抓取任何不是点但也有 column 和 Barr 的东西。或者相同的两个词以不同的顺序排列。

示例：

try = c("I am a sentence.I am a sentence and I contain Barr. I contain other things. I contain column as well.",
        "Here we go. I am a sentence and I contain column but also Barr. I only contain Barr. I am too.",
        "I am a sentence and I contain column but also Barr. I only contain Barr. I am too.",
        "I contain column and Barr. I have Barr and column. I don't.",
        "Hello. I contain Barr and column but also Barr. I only contain Barr. I am too.") 

k = sapply(try, function(x){
  str_extract(paste0(".",x), "(\\.[^.]*column[^.]*Barr[^.]*)|(\\.[^.]*Barr[^.]*column[^.]*)")
})
names(k) = NULL

结果：

[1] NA                                                    
[2] ". I am a sentence and I contain column but also Barr"
[3] ".I am a sentence and I contain column but also Barr" 
[4] ".I contain column and Barr"                          
[5] ". I contain Barr and column but also Barr"

如果您使用str_extract_all，请记住它会返回匹配列表。

[[1]]
character(0)

[[2]]
[1] ". I am a sentence and I contain column but also Barr"

[[3]]
[1] ".I am a sentence and I contain column but also Barr"

[[4]]
[1] ".I contain column and Barr" ". I have Barr and column"  

[[5]]
[1] ". I contain Barr and column but also Barr"

我添加了一个paste0(".",x) 以检测包含两个单词和第一个单词的句子（它们不以句点开头）。

Answer 3

这是一个更一般的尝试，不需要创建所需单词的每个排列，当需要两个以上的作品时很有帮助。

策略是找到每个单词的句子，然后找到结果的交集。

#split the long text into individual sentences.
sentences<-strsplit(try, "\\.")

#create list of matches for each desired word
columnlist<-lapply(sentences, function(x) {grep("(column)", x)})
barrlist<-lapply(sentences, function(x) {grep("(Barr)", x)})

#find intersection between lists
intersection<-lapply(seq_along(columnlist), function(i){intersect(columnlist[[i]], barrlist[[i]])} )

#extract the sentences out
answer<-sapply(seq_along(intersection), function(i) { 
  if(length(intersection[[i]])) 
    {trimws(sentences[[i]][intersection[[i]] ])}  
  else {NA}
})

结果

#[[1]]
#[1] NA
#
#[[2]]
#[1] "I am a sentence and I contain column but also Barr"